It is repairable and should be repaired before fretboard cracks. Truss rod will not keep it in one piece. Ideally you should try to scrape existing glue off the glueing surfaces, clean glueing surfaces, apply glue and clamp until dry. Scraping and cleaning are the difficult part.

How old is this bass? If you bought it locally and it's under warranty (it looks clean and new & the little sticker at the base of the headstock tells me it's fairly new), contact Washburn- that crack shouldn't have happened.

At this point, I would recommend not using this bass and de-tuning the strings, so remove the tension. The truss rod isn't a structural member, it's only there to provide/adjust the neck relief and, in fact, installation of a truss rod removes enough wood that the neck is weaker when the rod is slack. Also, don't use anything to clean the neck in the area of the crack. You don't want to contaminate the wood.

If the bass was bought from an off-shore seller or it's out of warranty and you don't want to tackle the repair, talk to someone who repairs furniture. Wood glue, clamps and wooden cauls makes this a relatively easy fix, but a little smoothing and possibly a finish touch-up will be needed.